This invention generally relates to a diaphragm or piston-type flushometer for use in a urinal, water closet, or the like. More particularly, the invention relates to a flushometer having a mechanism for removing air from a control chamber of the flushometer.
Piston-type flushometers having bypass orifice(s) are well known, as exemplified by the flush valve shown in U.S. Pat. No. 4,261,545, which is hereby incorporated herein by reference. Diaphragm-type flushometers also have bypass orifices, as exemplified by the flush valve shown in U.S. Pat. No. 6,616,119, which is hereby incorporated herein by reference. Another type of piston-type flushometer is taught, for example, in U.S. Pat. No. 6,913,239, which includes a domed inner cover defining the top of a control chamber. This type of piston valve has become commercially popular due to the benefits set forth in U.S. Pat. No. 6,913,239, namely that the inner cover allows for the outer cover to be made form a wider range of materials and also provides for improved reliability in operation of the flushometer.
Typically flushometers include a valve (piston or diaphragm) which seals the water inlet from the outlet of the valve body. The valve is controlled, at least in part, by utilizing pressure differentials, with a control chamber located within the valve body at its upper most interior. The control chamber functions to control the reseating of the valve upon the valve seat. An auxiliary valve controllably seals the control chamber from the outlet and bypasses provide metered control flow from the inlet to the control chamber. Thus, the control chamber can be pressurized to substantially the pressure of the inlet via communication through the bypasses. As the line pressure in the control chamber acts on a larger topside area of the piston or diaphragm than the inlet line pressure acts on smaller underside area of the piston, the valve remains closed under equal pressures. When the auxiliary valve is opened, the control chamber becomes exposed to a lower pressure (typically atmospheric pressure), i.e., smaller force, and the contents of the control chamber are vented into the outlet reducing the force exerted on the piston and allowing it to raise off the main seat creating an opening so that water from the inlet may flow to the outlet. The control chamber is repressurized via the bypass(s) and the valve closes as the force in the control chamber on the piston top increases past the force pushing on the underside of the piston body.
In ideal operation, the flushometer contains only water fluid within the inlet, valve, and control chamber, i.e. there is not air in the flush valve, such that water completely fills the volume. However, in certain circumstances, such as when the valve assembly is first installed, following maintenance, or where the water supply contains excessive dissolved gases (such as air), gases may be present in the valve assembly. More particularly, the gases will typically be located in the upper most interior of the valve assembly that is in fluid communication with the inlet, which is typically (see FIG. 1A and FIG. 1B) the control chamber. In particular, for commercial flushometers utilizing the domed inner cover taught by U.S. Pat. No. 6,913,239, the gases will have a tendency to be located at the top of the domed inner cover. Thus, gas may reside in the control chamber in such situations.
When air (gas) is present in the control chamber, the gallons per flush (GPF) will differ from the GPF when only water is present in the control chamber. The compressible “fluid” air combines with the incompressible fluid water causing inconsistent volume in the critical control chamber. A certain amount of the air will dissolve in the water and be removed over time, along with the water during repeated flush cycles. In prior art devices, this phenomenon results in a small amount of the air being removed each flush cycle, effectuating removal of the air (and a return to the “normal” GPF for a control chamber with only water) over a large number of flush cycles, understood to be over 50 cycles for some devices.